Water and wind are two environmental conditions that can easily turn a microphone porting system that works well in dry/calm conditions into one that is totally inoperative. For a device exposed to wet conditions, the surface tension of water can cover the small holes in the housing used for audio ports thereby completely blocking the audio path. Wind passing over the microphone port can generate small pressure pulses which the microphone cartridge converts into noise, generally referred to as wind noise.
Wind noise is problematic for both portable and mobile style microphones. Portable microphone products include communication devices, such as handheld radios and their associated accessories, having a microphone integrated therein. For example, some handheld radios operate in conjunction with an accessory having an additional separate microphone, such as a remote speaker microphone worn on a user's shoulder. A mobile microphone is generally a handheld device coupled to a vehicular radio mounted on or under the dashboard. Current microphone products exist for each microphone style that address either wind noise or water blockage problems, but not both.
Wind noise solutions have typically been incorporated into mobile style microphones by moving the microphone cartridge back away from the front housing and using a large ported surface area to settle the pressure pulses. Due to space limitations, made even more difficult with the addition of a speaker, this type of solution can not be readily implemented into a portable communication device.
Water blockage solutions have typically been incorporated into portable style microphones by adding an alternate acoustic path, referred to as a sneak path, which enables audio to reach the microphone even if the primary audio path becomes blocked. Wind noise performance for this type of porting scheme, or any direct porting scheme with the microphone mounted close to the front surface of the product, is usually poor. Felt is often used in microphone porting schemes to resist rain and dust intrusion, but given enough exposure, felt has a tendency to absorb water and allow water penetration which can completely block the microphone port.
Accordingly, it would be beneficial to have an improved audio porting scheme.